CHANGING PATTERNS OF SURVIVAL AND OUTCOME AT 4 YEARS OF CHILDREN WHO WEIGHED 500-999 G AT BIRTH

Objective: To evaluate the impact of changing perinatal practices on s urvival rates and 4 year neurodevelopmental outcome for infants of bir thweight 500-999 g. Methodology: The study was a tertiary hospital-bas ed prospective cohort study that compared survival, impairment and han dicap rates between two eras, July 1977 to December 1982 (era 1) and J anuary 1983 to June 1988 (era 2). All 348 live, inborn infants and 49 outborn infants of birthweight 500-999 g were prospectively enrolled i n a study of survival and outcome. Rates of survival, neurodevelopment al impairment and functional handicap at 4 years were compared between eras. Perinatal risk factors for handicap were also compared between eras. Results: Four year survival rates for inborn infants 500-999 g i mproved from 32.6% in era 1 to 49.2% in era 2 (OR 2.1,95% Cl 1.26-3.48 ) but for outborn infants the improvement between 31.8% and 53.6% was not significant. There were significant improvements in survival for i nborn infants in birthweights 800-899 g and 900-999 g between study pe riods. The rates of functional handicap between the first and second e ras (mild 10 vs 7%; severe or multiply severe 14 vs 16%) were not sign ificantly different Although the rate of cerebral palsy increased from 0 to 12% (P< 0.01) other rates of impairment such as blindness 0 vs 3 %, deafness 2 vs 2% and developmental delay 12 vs 11% did not change. The chance of a survivor being free of handicap remained unchanged at 78% and 76% for the two eras, respectively. Although the absolute numb er of intact survivors more than doubted (41 vs 83) so too did the num ber of severe or multiply severe handicapped survivors (7 vs 17). Mult ivariate logistic regression analysis for the entire study cohort reve aled male gender, multiple birth, prolonged mechanical ventilation and cerebral ventricular dilatation but not birthweight or gestational ag e to be independently associated with severe or multiply severe handic ap. Conclusions: The advances in neonatal intensive care for extremely low birthweight infants between July 1977 and December 1982 and Janua ry 1983-June 1988 resulted in an increased number of non-disabled surv ivors but had no impact on incidence of severe disability. The applica tion of prediction of mortality or severe handicap to clinical practic e has the potential to reduce the proportion and absolute number of se verely handicapped survivors.